Base isolated nebulizing device and methods

ABSTRACT

An aerosol generator comprises a vibratable member having a front, a rear, an outer periphery and a plurality of apertures extending between the front and the rear. A support element is disposed about the outer periphery of the vibratable member, and a vibratable element is coupled to the support element. The vibratable element is configured to vibrate the vibratable member at ultrasonic frequencies. An isolating structure is coupled to the support element and is configured to couple the aerosol generator to a support structure. The isolating structure has a mechanical vibrational impedance that is sufficient to substantially vibrationally isolate the aerosol generator from the support structure.

BACKGROUND OF THE INVENTION

This invention is related generally to the field of aerosolization ofliquids, and in particular to the aerosolization of liquids using anaerosol generator that operates at ultrasonic vibrational frequencies.More specifically, the invention relates to techniques for vibrationallyisolating an aerosol generator that is connected to another structure,such as the housing of an aerosolization device, when aerosolizing aliquid.

Aerosolization of liquids is an important aspect of many businesses. Forexample, liquids are commonly aerosolized in connection with drugdelivery, air humidification, deodorant or insecticide delivery, and thelike. One exemplary way to aerosolize liquids is by supplying liquid toa vibratable member having a plurality of apertures and vibrating thevibratable member at ultrasonic frequencies. One way to vibrate thevibratable member is by use of a piezoelectric transducer. Suchtechniques are described in, for example, U.S. Pat. Nos. 5,164,740;5,938,117; 5,586,550; 5,758,637 and 6,085,740, the complete disclosuresof which are herein incorporated by reference.

When vibrating such vibratable members at ultrasonic frequencies, thereis a need to ensure that a maximum amount of the vibrational energy istransferred from the piezoelectric transducer to the vibratable member,rather than to some surrounding structure. Otherwise, performance lossesor performance variations may occur because of the forces that aretransmitted through the material which couples the aerosol generator tosurrounding structures, such as the housing of an aerosolization device.

Hence, this invention is related to ways to maximize the amount ofvibrational energy transferred to the vibratable member, therebymaximizing the efficiency of the aerosol generator. In this way, therepeatability and performance of the aerosol generator are enhanced,irrespective of the devices into which the aerosol generators areintegrated.

SUMMARY OF THE INVENTION

The invention provides for the vibrational isolation of an aerosolgenerator from surrounding structures. In one embodiment, this isaccomplished by the design of an aerosol generator that comprises avibratable member having a front, a rear, an outer periphery and aplurality of apertures extending between the front and the rear. Asupport element is disposed about the outer periphery of the vibratablemember. A vibratable element is coupled to the support element and isconfigured to vibrate the vibratable member at ultrasonic frequencies.An isolating structure is coupled to the support element and isconfigured to couple the aerosol generator to a support structure, suchas the housing of an aerosolization device. The isolating structure hasa vibrational mechanical impedance that is sufficient to substantiallyvibrationally isolate the aerosol generator from the support structure.In this way, the aerosol generator may be operated at increasedefficiencies and in a repeatable manner when coupled to surroundingstructures.

Conveniently, the isolating structure and the support element may beintegrated into a single component, thereby facilitating itsmanufacture. In one aspect, the isolating structure may comprise aplurality of arms that extend from the support element. These arms mayhave a wide variety of shapes and contours. For example, the arms may bebent, crimped, curved, or the like to facilitate vibrational isolation.

In another aspect, the isolating structure may comprise one or moreelastomeric or plastic members. For example, the isolating structure maybe constructed of an elastomeric or plastic washer. Conveniently, thewasher may be coupled to the support element by forming tabs in thesupport element and inserting the washer between the tabs. As anotherexample, the isolating structure may be constructed of a plurality ofdiscrete elastomeric members or bellows that extend from the supportelement.

To facilitate vibrational isolation, the isolating structure may beconfigured so that it has a resonant frequency that is outside theoperating range of the aerosol generator. Such an operating range forthe aerosol generator may be about 50 kHz to about 250 kHz.

In a further aspect, the vibratable member may be dome shaped andinclude tapered apertures. Examples of such vibratable members aredescribed in U.S. Pat. Nos. 5,586,550, 5,758,637 and 6,085,740,previously incorporated by reference.

The invention further provides an exemplary method for aerosolizingliquids. Such a method utilizes an aerosol generator having a vibratablemember with apertures and a vibratable element to vibrate the vibratablemember. According to the method, liquid is supplied to the vibratablemember and the vibratable element is used to vibrate the vibratablemember at an ultrasonic frequency to eject liquid droplets through theapertures. During vibration, an isolating structure is used tosubstantially vibrationally isolate the aerosol generator to enhance theoperating performance of the aerosol generator. Further, the vibratablemember may be vibrated at a frequency that is different from afundamental frequency of the isolating structure to enhance theefficiency of the aerosol generator. As previously mentioned, a varietyof isolating structures may be used to vibrationally isolate the aerosolgenerator from any surrounding structures. Such isolating structuresalso have resonant frequencies outside of the operating range of theaerosol generator.

In a further embodiment, the invention provides a method for forming anaerosol generator. According to the method, an isolating structure isstamped or coined out of a sheet of material. A vibratable member havinga plurality of apertures is coupled to the isolating structure, and avibratable element, such as a piezoelectric transducer, is coupled tothe isolating structure or the vibratable member. The vibratable elementis used to vibrate the vibratable member at ultrasonic frequencies whilethe isolating structure is used to vibrationally isolate the aerosolgenerator from surrounding structures. By forming the isolatingstructure in this way, the cost of producing the aerosol generator maybe greatly reduced and the aerosol generator may be produced in highervolumes.

In one aspect, the isolating structure comprises an annular member and aplurality of arms extending from the annular member. In another aspect,the arms are bent or crimped after the isolating structure has beenstamped. In a further aspect, the vibratable member is coupled across acentral opening of the annular member, and the vibratable elementcomprises an annular piezoelectric element that is coupled to theannular member.

Another method for forming an aerosol generator uses a support elementhaving an outer periphery. A plurality of tabs are formed in the outerperiphery of the support element. This may be accomplished by making apair of cuts in the support element and then bending the materialbetween the cuts away from the support element. A vibratable memberhaving a plurality of apertures is coupled to the support element, and avibratable element is coupled to the support element or the vibratablemember and is vibratable at ultrasonic frequencies. A gasket is coupledabout the support element, with the gasket being received into the tabs.The gasket has a mechanical vibrational impedance that is sufficient tosubstantially vibrationally isolate the aerosol generator. Such aprocess is useful in producing an isolated aerosol generator in a timeand cost efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear perspective view of one embodiment of an aerosolgenerator according to the invention.

FIG. 2 is a rear perspective view of an isolating structure of theaerosol generator of FIG. 1 prior to assembly of the aerosol generator.

FIG. 3 illustrates an aerosolization device having the aerosol generatorof FIG. 1.

FIG. 4 is a front perspective view of another embodiment of an aerosolgenerator according to the invention.

FIG. 5 is a side perspective view of a further embodiment of an aerosolgenerator according to the invention.

FIG. 6 is a rear perspective view of yet another embodiment of anaerosol generator according to the invention.

FIG. 7 is a rear perspective view of still another embodiment of anaerosol generator according to the invention.

FIG. 8 is a rear perspective view of one particular embodiment of anaerosol generator according to the invention.

FIG. 9 is cross sectional view of another embodiment of an aerosolgenerator according to the invention.

FIG. 10 is a perspective view of a support element and an isolatingstructure of the aerosol generator of FIG. 9.

FIG. 11 is a perspective view of the support element of FIG. 10 prior tothe formation of tabs that are employed to hold the isolating structure.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The invention provides techniques and devices to vibrationally isolatean aerosol generator from surrounding structures to which the aerosolgenerator is coupled. In some cases, the surrounding structures will bethe housing of an aerosolizer or nebulizer, or various structures withinsuch devices. Such aerosolization or nebulization devices can havecomplex geometry's as well as complicated fluid delivery and packagingrequirements that can affect the operation of the aerosol generator.

The aerosol generators of the invention may comprise a vibratable memberhaving a plurality of apertures, such as an aperture plate, throughwhich liquid droplets are ejected and a piezo electric transducer tovibrate the aperture plate. The transducer is configured to vibrate theaperture plate at ultrasonic frequencies, typically within the rangefrom about 50 kHz to about 250 kHz. Non-limiting examples aerosolgenerators utilizing such components are described in U.S. Pat. Nos.5,164,740; 5,938,117; 5,586,550; 5,758,637 and 6,085,740, incorporatedherein by reference.

The aerosol generators of the invention utilize an isolation system thatis designed to accommodate nearly all types of external interfaces toenhance the repeatability and performance of the aerosol generator. Inthis way, the aerosol generators may be placed into a wide variety ofcomplex aerosolization or nebulization devices without significantlycompromising their operation. The isolation systems have a mechanicalvibrational impedance that prevents the force transmitted at the edge ofthe aerosol generator from reaching the surrounding structure. Such aphenomenon may be characterized as the transmissibility and is definedas the ratio of the force experienced by the surrounding structure tothe force produced at the edge of the aerosol generator. According tothe invention, the transmissibility is less than about 30%, morepreferably less than about 20%, and most preferably less than about 10%.In some cases the transmissibility has been measured to be less thanabout 6% and at about 2% to 3% at resonance.

The isolation system may be constructed of either discrete or continuouselements and may have a wide variety of shapes and sizes. For example,the isolation system may be constructed of thin metals arms, elastomerbushings, plastic legs, elastomer edges, and the like. Types ofmaterials that may be used to construct such elements include silicone,urethane, elastomers, thin or curved metals, and the like.

The isolating systems of the invention are also configured to have aresonant frequency that is outside of the operating frequency of theaerosol generator. In this way, the isolating structure does notresonate during operation of the aerosol generator, thereby enhancingthe performance and repeatability of the aerosol generator.

Another feature of the invention is that the isolating systems may beincorporated into the aerosol generators in such a way that the aerosolgenerators may be fabricated in high volumes and at reasonable costs.This may be accomplished, for example, by utilizing an isolatingstructure to both vibrationally isolate the aerosol generator and tosupport the aperture plate. Such isolating structures may convenientlybe formed by stamping, coining, molding, and the like.

Referring now to FIG. 1, one embodiment of an aerosol generator 10having an isolating system will be described. Aerosol generator 10comprises a vibratable member 12 having a front (hidden from view), arear 14 and an outer periphery 16. Although not shown, vibratable memberhas a plurality of apertures that taper from rear 14 to the front.Examples of vibratable members that may be used with the invention aredescribed generally in U.S. Pat. Nos. 5,164,740; 5,938,117; 5,586,550;5,758,637 and 6,085,740, incorporated by reference. As shown, vibratablemember 12 is dome shaped in geometry. However, it will be appreciatedthat other shapes and sizes of vibratable members may be used, and theinvention is not intended to be limited to a specific type of vibratablemember.

Vibratable member 12 is coupled to an isolating structure 18 that alsofunctions as a support member to support vibratable member 12. Isolatingstructure comprises an annular body 20 and a set of arms 22 that areused to couple aerosol generator 10 to another structure, such as thehousing of an aerosolization device. Annular body 20 is secured aboutouter periphery 16 of vibratable member 12 so that the center ofvibratable member is free to eject liquid droplets. Coupled to annularbody 20 is an annular piezo electric element 24 that is used to vibratevibratable member 12 when current is supplied to piezo electric element24.

In use, arms 22 are employed to prevent the transmission of forces atthe outer edge of body 20 from reaching surrounding structures so thataerosol generator 10 is substantially vibrationally isolated from anysurrounded structures to which arms 22 may be coupled. In this example,arms 22 may be constructed of aluminum, steel, elastomers, plastic andthe like and may have one or more bends to facilitate mounting ofaerosol generator 10 to another structure and to prevent forcetransmission. Further, although shown with three arms, aerosol generator10 may be constructed to have different numbers of arms, such a two,four, five, or the like. With such a construction, aerosol generator 10may be operated in a repeatable manner, i.e., the aerosol generator isable to consistently produce droplets within a given size range andwithin a given range of flow rates. Further, this embodiment has shownto have a transmissibility at about 2% at resonance.

As shown in FIG. 2, isolating structure 18 may be stamped from a sheetof material. Once stamped, vibratable member 14 and piezo electricelement 24 may be bonded to body 22. Arms 22 may also be bent to thedesired shape. Such a process lends itself to high volume production atreasonable costs.

Referring now to FIG. 3, aerosol generator 10 is shown coupled to anaerosolization device 30. Device 30 comprises a housing 32 to hold thevarious components of aerosolization device 30. Housing 32 furtherincludes a mouthpiece 34 and one or more vents (not shown) to permit airto enter into housing 32 when a user inhales from mouthpiece 34.Disposed within housing 32 is aerosol generator 10 of FIG. 1. However,it will be appreciated that any of the aerosol generators describedherein may be placed into housing 32. Aerosol generator 10 is coupled tohousing 32 by arms 22 that also serve as an isolating structure tovibrationally isolate aerosol generator 10 from housing 32 in a mannersimilar to that described herein.

Aerosolization device 30 further includes a canister 36 having a supplyof liquid that is to be aerosolized by aerosol generator 10. Canister 36may include a metering valve to place a metered amount of liquid ontoaperture plate 16. Although not shown, a button or the like may beemployed to dispense the volume of liquid when requested by the user.

Housing 32 includes an electronics region 38 for holding the variouselectrical components of aerosolization device 30. For example, region38 may include a printed circuit board 40 which serves as a controllerto control operation of the aerosol generator 10. More specifically,circuit board 40 may send (via circuitry not shown) an electrical signalto the piezoelectric element 24 to cause aperture plate 16 to bevibrated. A power supply P, such as one or more batteries, iselectrically coupled to circuit board 40 to provide aerosolizationdevice 30 with power.

FIG. 4 illustrates an alternative embodiment of an aerosol generator 70.Aerosol generator 70 comprises a vibratable member 72 having a front 74,a rear (not shown) and a plurality of apertures. Vibratable member 72 iscoupled to a support member 76 that also supports a piezo electricelement 78. Extending from support member 76 are a set of curved arms 80that function as an isolating structure to vibrationally isolate aerosolgenerator from other structures to which arms 80 are coupled. Arms 80may be constructed materials similar to those described in connectionwith FIG. 1. Further, although shown with only one curve, in some caseseach arm may include multiple curves or bends to facilitate vibrationalisolation of aerosol generator 70.

FIG. 5 illustrates another embodiment of an aerosol generator 82 havingan alternative isolation system. Aerosol generator 82 is similar toaerosol generator 70 except for the configuration of the arms. Forconvenience of discussion, similar elements will be referred to with thesame reference numerals used in FIG. 4. Aerosol generator 82 utilizes aset of angled arms 84 that are connected to support member 76. Althoughshown with one angled bend, arms 84 may alternatively have multipleangled bends, that may or may not have the same angle of bend.

FIGS. 6–8 illustrate further alternative embodiments of aerosolgenerators having different isolation systems. These aerosol generatorsare similar to aerosol generator 70 except for the isolating structure.For convenience of discussion, similar elements will be referred to withthe same reference numerals used in FIG. 4. FIG. 6 illustrates anaerosol generator 88 having a set of tabs 90 that are connected tosupport member 76 and are used to vibrationally isolate aerosolgenerator 88 from surrounding structures to which tabs 90 are connected.Tabs 90 may be constructed of materials such as those described withprevious embodiments, and may be more or less in number than shown inthe drawing. Tabs 90 may optionally include mounting holes 92 tofacilitate mounting of the tabs to another structure. In some cases,tabs 90 and support structure 76 may be formed together in an insertmolding process as described generally in copending U.S. patentapplication Ser. No. 09/848,111, filed on the same date as the presentapplication, incorporated herein by reference.

FIG. 7 illustrates an aerosol generator 94 having an elastomeric ring 96that is coupled about the outer periphery of support member 76.Elastomeric ring 96 serves as an isolating structure to vibrationallyisolate aerosol generator 94 from surrounding structures to which ring96 may be coupled. Alternatively, a plastic material may be used to formring 96.

FIG. 8 illustrates an aerosol generator 98 having a set of discreteelastomeric elements 100 that are disposed about the outer periphery ofsupport member 76. These elements may be constructed of elastomeric orplastic materials similar to those described in FIG. 7 and may be moreor less in number than three. Elements 100 are employed to vibrationallyisolate aerosol generator 98 from surrounding structures to whichelements 100 are connected.

Shown in FIG. 9 is a cross sectional view of an aerosol generator 110having an isolation system and which may be manufactured in a time andcost efficient manner. Aerosol generator 110 is constructed of a supportelement 112 that is used to hold a vibratable member 114 having aplurality of apertures in a manner similar to that described with otherembodiments. As also shown in FIG. 10, support element 112 has a centralaperture 116 across which vibratable member 114 is positioned and acircular outer periphery 118. Coupled to support element 112 is avibratable element 120 to vibrate vibratable member 114 whenaerosolizing a liquid.

Support element 112 may be manufactured by stamping support element 112from a sheet as material such that is it in the shape of a disc orwasher. As shown in FIG. 11, pair of cuts 122 and 124 are formed insupport element 112 at the outer periphery 118 to form a set of tabs126. Tabs 126 are then pressed or bent away from support element 112 toform a slot between tabs 126 and support element 112 as shown in FIG. 9.An isolating member 128 may then be inserted about outer periphery 118by inserting isolating member 128 between tabs 126. Conveniently,isolating member 128 may comprise a resilient gasket that may be slippedbetween tabs 126. As with other embodiments, isolating member 128 may beused to vibrationally isolate the aerosol generator from surroundingstructures.

The invention has now been described in detail for purposes of clarityof understanding. However, it will be appreciated that certain changesan modifications may be practiced within the scope of the appendedclaims.

1. An aerosol generator system comprising: an aerosol generatorcomprising a vibratable member having a front, a rear and a plurality ofapertures extending between the front and the rear, wherein the aerosolgenerator is configured to produce liquid droplets when operated at acertain vibrational frequency; an isolating structure operably coupledto the aerosol generator and that is configured to couple the aerosolgenerator to a support structure, wherein the isolating structure has avibrational impedance that is sufficient to substantially vibrationallyisolate the aerosol generator from the support structure, and whereinthe isolating structure comprises a plurality of arms extending from theaerosol generator.
 2. An aerosol generator system as in claim 1, whereinthe plurality of arms extended from a support element disposed about anouter periphery of the vibratable member; and a vibratable elementcoupled to the support element, the vibratable element being configuredto vibrate the vibratable member at ultrasonic frequencies, and whereinthe isolating structure and the support element are integrally formedtogether.
 3. An aerosol generator system as in claim 2, wherein theisolating structure is configured such that the ratio of forcestransmitted to the support structure to forces at an outer edge of thesupport element is less than about 30%.
 4. An aerosol generator systemas in claim 3, wherein the ratio is less than about 20%.
 5. An aerosolgenerator system as in claim 2, wherein the isolating structure hasresonant frequencies that are outside of an operating frequency range ofthe aerosol generator.
 6. An aerosol generator system as in claim 5,wherein the operating frequency range is about 50 kHz to about 250 kHz.7. An aerosol generator system as in claim 1, wherein the arms have acontoured shape.
 8. An aerosol generator system as in claim 1, whereinthe vibratable member has a center portion containing the apertures,wherein the center portion is dome shaped in geometry, and wherein theapertures taper from the rear to the front.
 9. An aerosolization devicecomprising: a housing; and an aerosol generator disposed within thehousing, the aerosol generator comprising a vibratable member having afront, a rear and a plurality of apertures extending between the frontand the rear, wherein the vibratable member is configured to vibrate atultrasonic frequencies, an isolating structure coupled to the aerosolgenerator, and operably connected to the housing, wherein the isolatingstructure has a vibrational impedance that is sufficient tosubstantially vibrationally isolate the aerosol generator from thehousing; and wherein the isolating structure comprises a plurality ofarms extending from the aerosol generator.
 10. A device as in claim 9,wherein the plurality of arms extended from a support element disposedabout an outer periphery of the vibratable member, a vibratable elementcoupled to the support element to vibrate the vibratable member, whereinthe isolating structure and the support element are integrally formedtogether.
 11. A device as in claim 10, wherein the isolating member isconfigured such that the ratio of forces transmitted to the supportelement to forces at an outer edge of the support element is less thanabout 30%.
 12. A device as in claim 11, wherein the ratio is less thanabout 10%.
 13. A device as in claim 9, wherein the arms have a contouredshape.
 14. A device as in claim 9, wherein the isolating structure hasresonant frequencies that are outside of an operating frequency range ofthe aerosol generator.
 15. A device as in claim 14, wherein theoperating frequency range is about 50 kHz to about 250 kHz.
 16. A deviceas in claim 9, wherein the vibratable member has a center portioncontaining the apertures, wherein the center portion is dome shaped ingeometry, and wherein the apertures taper from the rear to the front.17. A method for aerosolizing a liquid, the method comprising: providingan aerosol generator comprising a vibratable member having a front, arear, and a plurality of apertures extending between the front and therear, and a vibratable element to vibrate the vibratable member;supplying a liquid to the rear of the vibratable member; and vibratingthe vibratable member with the vibratable element to eject liquiddroplets through the apertures while substantially vibrationallyisolating the aerosol generator with an isolating structure that isoperably coupled to a support structure; wherein the isolating structurecomprises a plurality of arms extending from the aerosol generator,wherein the isolating structure is configured to vibrationally isolatethe aerosol generator from the support structure.
 18. A method as inclaim 17, further comprising vibrating the vibratable member at afrequency that is different than a resonant frequency of the isolatingstructure, and wherein the vibratable member is vibrated at a frequencyin the range from about 50 kHz to about 250 kHz, and wherein the ratioof forces transmitted to the support structure to forces at an outeredge of the aerosol generator is less than about 30%.